ZrO2/PMMA Nanocomposites： Preparation and Its Dispersion in Polymer Matrix

ZrO2/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent （Z-6030） modified ZrO2 nanoparticles, and the morphology, size and its distribution of nanocomposite particles are investigated. Scanning electron microscopy （SEM） images demonstrate that the methyl methacrylate （MMA） feeding rate has a significant effect on the particle size and morphology. When the MMA feeding rate decreases from 0.42 ml-min-1 to 0.08 ml. min-1, large particles （about 200-550.nm） will not form, and the size distribution become narrow （36-54 nm）. The average nanocomposite particles size increases from 34 nm to 55 nm, as the MMA/ZrO2 nanoparticles mass ratio increased from 4 ： 1 to 16 ： 1. Regular spherical ZrO2/PMMA nanocomposite particles are synthesized when the emulsifier OP-10 concentration is 2 mg.m1-1. The nanocomposite particles could be mixed with VAc-VeoVa10 polymer matrix just by magnetic stirring to prepare the ZrOE/PMMA/VAc-VeoVal0 hybrid coatings. SEM and atomic force microscopy （AFM） photos reveal that the distribution of the ZrO2/PMMA nanocomposite particles in the VAc-VeoVal0 polymer matrix is homogenous and stable. Here, the grafted-PMMA polymer on ZrO2 nanoparticles plays as a bridge which effectively connects the ZrO2 nanoparticles and the VAc-VeoVal0 polymer matrix with improved comparability. In consequence, the hybrid coating with good dispersion stability is obtained.

Influence of polymer dispersants on dispersion stability of nano-TiO_2 aqueous suspension and its application in inner wall latex paint

The effects of SN5040 and polyethylene glycol（PEG） individually and in combination on the dispersion stability of nano-TiO2 aqueous suspension were investigated by ultraviolet-visible absorption spectroscopy. The adsorption mechanism of these dispersants was detected by zeta potential, isothermal absorption and FTIR analysis. It is found that SN5040 is superior for stabilizing nano-TiO2 in aqueous suspension to PEG in basic region, and the optimum mass fraction of SN5040 addition is 3%. In the case of NaCl addition, the optimum value increases with .the increase of NaCl concentration in the solution. When the mixture of SN5040 and PEG is employed, the antagonism appears preponderant. When SN5040 and PEG are added sequentially, the synergistic reaction takes place. The synergistic reaction can be attributed to the mechanism that PEG adsorption decreases the electronic repulsion between SN5040 molecules, which results in the increase of SN5040 adsorption density. PEG is adsorbed by the interaction with the pre-adsorbed SN5040 layer. Furthermore, the modified inner wall latex paint with well dispersed nano-YiO2 suspension is endowed with excellent ultraviolet absorption and antibacterial properties.

Preparation,Dispersion and Tribological Properties of Oleophilic Lanthanum Hydroxide/Graphene Oxide Nanocomposites

Lanthanum hydroxide/graphene oxide nanocomposites(La(OH)3/GO)modified by octadecylamine(OCA),oleylamine(OLA),and polyvinylpyrrolidone(PVP)were prepared,respectively,as the base oil additives.The dispersion stability of different modified La(OH)3/GO in base oil was studied by means of centrifugation.The tribological properties of oleophilic La(OH)3/GO in base oil were investigated using an UMT ball-disc tribometer.The micro-morphology and chemical composition of the worn surface were characterized by 3 D laser microscope,SEM,EDS,XPS,and Raman spectroscopy,respectively.The wettability performance of the worn surface was also studied based on the contact angle measurements.The test results showed that the OLA-La(OH)3/GO nanocomposites had good dispersion stability in base oil.The anti-wear performance of base oil was improved significantly by the addition of OLA-La(OH)3/GO nanocomposites.The characterizations of worn surface showed that the OLA-La(OH)3/GO nanocomposites could form the metal oxide and graphene protective films effectively on the friction interface and thus increased the oil wettability of the worn surface,thereby resulting in an improved wear resistance.

Beneficial effects of high-pressure homogenization on the dispersion stability of aqueous hydrolysate from Mytilus edulis

Owing to the formation of aggregation and gelation during storage,certain proteins and peptides exhibit limited applications in aqueous protein food products.The purpose of this study was to investigate the influence of homogenization and xanthan gum addition on the dispersion stability of Mytilus edulis hydrolysate(PHM).High-pressure homogenization(HPH)at 360 and 40 bar in the first and second values,respectively,and adding xanthan gum at a concentration of 1 mg/mL showed significantly improvement on the stability of the PHM solution.PHM-xanthan gum solutions(PHMX)showed the highest polypeptide precipitation rate and turbidity retention rate compared with those of PHM.Moreover,the centrifugal precipitation rate of PHMX without HPH was higher than that of homogeneous PHMX.After HPH treatment at 400 bar,the percentage of smaller particles in PHM and PHMX was increased,the aqueous system became more uniform,and the fluorescence intensity reached its maximum.HPH pretreatment improved the polypeptide dispersion stability and turbidity retention rate of PHM and PHMX and reduced the fluorescence intensity.The interactions of xanthan gum and polypeptide render the network microstructure more uniform under the conditions of homogenization,thus improving the dispersion stability of PHMX solutions.Therefore,under the premise of adding xanthan gum,HPH can better enhance the dispersion stability of the polypeptide in PHM.

Preparation of SiO_2 Nanoparticles by Ion Exchanging and Study on Their Dispersion Stability

By adopting sodium silicate as a major material,SiO_2 nanoparticles (size in 8-15nm) water-dispersiod was prepared by ion exchanging.The effects of sodium silicate concentration,surface-modifying time,temperature and technological conditions on their diameter,size distribution and dispersion stability were also studied.The result show that,the hydrophilic lipophlic and hydrophilic-lipophilic SiO_(2) nanoparticles water-dispersoid can be prepared through different kinds of surface-modifiers and the optimum reaction conditions have been determined as follows:sodium silicate solution concentration:8w%;silicone dosage:3% of the total mass of nano SiO_(2) water-dispersoid;adding way and time of surface-modifier:continual dropping for 2h;surface-modifying temperature:60-70℃.

Preparation of SiO_2 Nanoparticles by Silicon and Their Dispersion Stability

Silicon dioxide sol was synthesized by silicon in the presence of alkali catalyst. SiO_2 nanoparticles (size in 8-15 nm) aqueous dispersion was prepared by using dispersion and surface modification in situ. The effects of reaction time, temperature, medium pH value, dispersant and surface-modifier on their diameters, sizes distribution and dispersion stability were also studied.The experimental results show that the preparation method can effectively resolve the dispersion stability of SiO_2 nanoparticles in water.

An IR Study of the Dispersion Stability of Catalyst Powders Dispersed in Solutions of Linear Saturated Polyesters

The conformation of polymers at the solid-liquid interface has been the subject of considerable interest in the fundamental theory and applied practice. In paints and printing inks, dispersions of pigment or filler powders in polymeric binder solutions have to be maintained in the colloidal state. One of the stabilizing mechanisms for paint is the steric stabilization. On the other hand, in the formation reaction of polymer at the solid-liquid interface took place between monomer solutions and solid

Surface-functionalized cellulose nanocrystals(CNC)and synergisms with surfactant for enhanced oil recovery in low-permeability reservoirs

Nanocellulose,a natural polymeric nanomaterial,has attracted significant attention in enhanced oil recovery(EOR)applications due to its abundance,nanoscale,high oil-water interfacial adsorption ef-ficiency.In this study,surface-functionalized cellulose nanocrystals(SF-CNCs)were prepared via hy-drochloric acid hydrolysis and chemical modification,with adaptable nanosize and considerable dispersion stability in low-permeability reservoirs.The SF-CNCs were structurally characterized by FT-IR,Cryo-TEM,which have a diameter of 5-10 nm and a length of 100-200 nm.The SF-CNC dispersions possessed higher stability and stronger salt-tolerance than those of corresponding CNC dispersions,due to the strong hydrophilicity of the sulfonic acid group.It was synergistically used with a non-ionic surfactant(APG1214)to formulate a combined flooding system(0.1 wt%SF-CNC+0.2 wt%APG1214).The combined flooding system exhibits strong emulsification stability,low oil-water interfacial tension of o.03 mN/m,and the ability to alter the wettability for oil-wetting rocks.Furthermore,the combined system was_able to provide an optimum EOR efficiency of 20.2%in low-permeability cores with 30.13×10^(-3)μm^(2).Notably.it can enlarge the sweep volume and increase the displacement efficiency simultaneously.Overall,the newly formulated nanocellulose/surfactant combined system exhibits a remarkable EoR performance in low-permeability reservoirs.

High-concentration dispersions of exfoliated MoS2 sheets stabilized by freeze-dried silk fibroin powder

Liquid-phase exfoliation （LPE） is an attractive method for the scaling-up of exfoliated MoS2 sheets compared to chemical vapor deposition and mechanical cleavage. However, the MoS2 nanosheet yield from LPE is too small for practical applications. We report a facile method for the scaling-up of exfoliated MoS2 nanosheets using freeze-dried silk fibroin powders. Compared to MoS2 dispersion in the absence of silk fibroin powder, sonicated MoS2 dispersions with silk fibroin powder （MoSJSilk dispersion） show noticeably higher exfoliated MoS2 nanosheet yields, with suspended MoS2 concentrations in MoS2/Silk dispersions sonicated for 2 and 5 h of 1.03 and 1.39 mg.mL-1, respectively. The MoS2 concentration in the MoS2/Silk dispersion after centrifugation above 10,000 rpm is more than four times that without the silk fibroin. The size of the dispersed silk fibroin is controlled by the change of centrifugation rate, showing the removal of silk fibroin above tens of micrometers in size after centrifugation at 2,000 rpm. Size-controlled silk fibroin biomolecules combined with MoS2 nanosheets are expected to increase the practical use of such materials in fields related to tissue engineering, biosensors and electrochemical electrodes. Atomic force microscopy and Raman spectroscopy provide the height of the MoS2 nanosheets spin-cast from MoS2/Silk dispersions, showing thicknesses of 3--6 nm. X-ray photoelectron spectroscopy and X-ray diffraction indicate that the outermost surface layer of the hydrophobic MoS2 crystals interact with oxygen-containing functional groups that exist in the hydrophobic part of silk fibroins. The amphiphilic properties of silk fibroin combined with the MoS2 nanosheets stabilize dispersions by enhancing solvent-material interactions. The large quantities of exfoliated MoS2 nanosheets suspended in the as-synthesized dispersions can be utilized for the fabrication of vapor and electrochemical devices requiring high MoS2 nanosheets contents.

Influence factors on thermal conductivity of ammonia-water nanofluids

In order to investigate the mechanism of nanoparticles enhancing the heat and mass transfer of the ammonia-water absorption process,several types of binary nanofluids were prepared by mixing Al2O3 nanoparticles with polyacrylic acid(PAA),TiO2 with polyethylene glycol(PEG 1000),and TiN,SiC,hydroxyapatite(noodle-like) with PEG 10000 to ammonia-water solution,respectively.The thermal conductivities were measured by using a KD2 Pro thermal properties analyzer.The influences of surfactant and ammonia on the dispersion stabilities of the binary nanofluids were investigated by the light absorbency ratio index methods.The results show that the type,content and size of nanoparticles,the temperature as well as the dispersion stability are the key parameters that affect the thermal conductivity of nanofluids.For the given nanoparticle material and the base fluid,the thermal conductivity ratio of the nanofluid to the ammonia-water liquid increases as the nanoparticle content and the temperature are increased,and the diameter of nanoparticle is decreased.Furthermore,the thermal conductivity ratio increases significantly by improving the stabilities of nanofluids,which is achieved by adding surfactants or performing the proper ammonia content in the fluid.

Performance of Polyaniline-coated Short Carbon Fibers in Electromagnetic Shielding Coating

Combined nitric acid oxidation method and polyaniline （PANI）-coated method were applied to modify the surface properties of short carbon fibers （SCF）. The electrical and mechanical properties of acrylic coatings with 50 wt pct PANI-coated carbon fiber were investigated by using scanning electron microscope （SEM）, UV-Vis spectrophotometer, four-probe method and the coaxial cable method. The results of the pH measurement and XPS （X-ray photoelectron spectroscopy） patterns showed that the oxygen functional groups, such as -OH and -COOH, were attached on the carbon fiber surfaces after oxidation treatment. The XPS analysis of PANl-coated oxidized SCF （PAOSCF） revealed that PANI may bond on the surface of oxidized SCF with chemical bonds. SEM images and surface roughness analyses showed that PANl-coated layer changed the surface morphology. Compared with SCF/acrylic coating, the surface resistivity of PAOSCF/acrylic coating decreased from17.1 to 5.3 Ω/sq and the shielding efficiency （SE） value increased from 1.54 to 23.3 dB.

Effect of Hyperbranched Poly(amine-ester) Grafted Nano-SiO_2 on Reinforcement and Toughness of PVC

Nano-SiO2 was modified using silane coupling agent （KH-550） and hyperbranched poly（amine-ester） respectively, and Poly（vinyl chloride） （PVC）/modified nano-SiO2 composites were made by melt-blending. The composites＇ structures andmechanical properties were characterized by transmission electron microscopy（TEM）, sanning electronic microscopy（SEM） and electronic universal testing machine. The results. show that nano-SiO2 grafted by hyperbranched poly （amine-ester） increases obviously in dispersion in PVC matrix, and mechanical properties of PVC are effectively improved. Moreover, it was found that mechanical properties of PVC/nano-SiO2 composites reach the best when weight percent of nano-SiO2 in PVC matrix is 1%. Compared with crude PVC, the tensile strength of hyperbranched poly （amine-ester） grafted nano-SiO2/ PVC composite increases by 24.68 % and its break elongation, flexural strength and impact strength increase by 15.73%, 4.07% and 1 841.84%, respectively. Moreover, the processing of the composites is improved.

Catalytic methanation of syngas over Ni-based catalysts with different supports

Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.

Stability and Lubrication Properties of Nano Oxides in Base Oil

The target products were prepared by homogeneous precipitation method using SDS and PEG 800, respectively, as surfactant at a reaction temperature of 95 ℃ for 3 h, followed by calcination at 400 ~C for 3 h. The samples were charac- terized and analyzed by XRD, SEM, FTIR and zeta potential measurements. The products were modified with different sur- factants to improve their dispersion stability, both the amount and the best zeta potential values of which were identified in this work. The surface-modified nano-particles were added at a mass fraction of 1.0%, 2.0%, 3.0%, and 4.0%, respectively, into the base oil. It was showed that the additive in base oil has good oil solubility without detectable corrosion of copper stripe, and had excellent behavior in terms of anti-wear performance and lower friction coefficient.

Novel Method of Hyperbranched Polymer Modified Nano-SiO_2-Grafting Hyperbranched Poly(amide-ester) from Nano-SiO_2 by One-Step Polycondensation

A new method of surface chemical modification of nano-SiO2 is proposed in this paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO2 reacted with AB2-type monomer （N, N-dihydroxyethyl-3-amino methyl propionate） by one-step polycondensation. And the product＇s Fourer transform infrared （FTIR） graphs and transmission electron microscopy（TEM） images proved that hyperbranched poly （amine-ester） was grafted on nano-SiO2 surface successfully. Results show that the modified nano-SiO2 exhibits excellent dispersion and stability in some solvents such as alcohol and chloroform.

The Influence of Yttrium Isopropoxide on the Mechanical Properties of SiC_w-reinforced AIN Ceramics

By using self-made metal-alkoxide yttrium isopropoxide as a sintering additive and disperser of whisker, the SiC whisker reinforced AIN ceramics was prepared. Its apparent density is 99.5 percent of the theoretical density; its flexural strength and fracture toughness are 681 MPa and 5.21 MPa·m1/2 respectively. Comparing the result with that by applying Y2O3 powder as a sintering additive, the flexural strength is increased by 25% and the fracture toughness is increased by 33% . The dispersity of whisker by increased yttrium isopropoxide is significantly better than that by Triton X-100.

STUDY OF NANOSIZED SILICA GRAFIED WITH HYPERBRANCHED POLY(AMINE-ESTER)

A new method to chemically modify the surface of nanosized-SiO2 was studied in this paper.Nanosized-SiO2 was grafted with hyperbranched poly(amin ester)through one-spot polycondensation between AB2 monomer and active hydroxyl on silica surface in present of catalyst.Compared with the results of FTIR and TEM,it is found hyperbranched poly(amin ester)is successfully grafted on the surface of nanosized-SiO2 and the surface properties have been changed with an expected way.The results indicate that nanosized-SiO2 grafted with hyperbranched poly(amin ester)has better dispersion in the ethanol or chloroform than that unmodified.

Cellulose Nanocrystals-Coated Polylactide(PLA) Microspheres Obtained via a Pickering Emulsion Approach

In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were prepared using CNCs as efficient stabilizers without any additional surfactant. The microspheres were successfully fabricated after volatilization of the solvent. What's more,the size of microspheres could be controlled by fabrication parameters.

Stability of partially deacetylated chitin nano-fiber dispersions mediated by protonic acids

Partially deacetylated chitin nano-fiber(DAChN)dispersions were prepared using mechanical treatment of partially deacetylated crab shellα-chitin under acidic conditions mediated by various protonic acids.The representative organic acids had a better efficiency in terms of mediating the nanofibrillation of chitin fibers in comparison to the inorganic acid(HCl).The DAChN dispersed in water at a pH of 3.5 mediated by gluconic acid exhibited the highest yield of nano-fibers(88.6%),followed by succinic,itaconic,and ascorbic acids with a nano-fiber yield of 79.9%,73.3%and 66.0%,respectively.The pH,conductivity,viscosity,and light transmittance of dispersions were assessed under different storage times.All of the tested DAChN dispersions were stable for at least 15 weeks at 4℃.

Nanolubricant additives: A review

Using nanoadditives in lubricants is one of the most effective ways to control friction and wear,which is of great significance for energy conservation,emission reduction,and environmental protection.With the scientific and technological development,great advances have been made in nanolubricant additives in the scientific research and industrial applications.This review summarizes the categories of nanolubricant additives and illustrates the tribological properties of these additives.Based on the component elements of nanomaterials,nanolubricant additives can be divided into three types:nanometal-based,nanocarbon-based,and nanocomposite-based additives.The dispersion stabilities of additives in lubricants are also discussed in the review systematically.Various affecting factors and effective dispersion methods have been investigated in detail.Moreover,the review summarizes the lubrication mechanisms of nanolubricant additives including tribofilm formation,micro-bearing effect,self-repair performance,and synergistic effect.In addition,the challenges and prospects of nanolubricant additives are proposed,which guides the design and synthesis of novel additives with significant lubrication and antiwear properties in the future.